robert1 wrote:Piston rock would just be polished wear above the ring. That is detonation from too lean, too much timing, not enough fuel flow, too much compression. This goes back I believe to your first visits here talking about aluminum wrist pins. By the time that you get to this level of HP the operator should know very well what they are doing. Just having enough money to buy this much HP is not very helpful. That would be the intake side and that is always the side that shows the first signs of detonation. Too bad something like this ends up in court as the builder has zero control over what the user might do to the engine. Experience is very expensive. I had a guy many years ago the burned the number 3 piston in a SBC alcohol motor 3 weeks in a row. I kept telling them it was too lean. After sending the carb back several times they finally got it right. I had to stay late each week to make sure they were able to race each week.
Dave Koehler wrote:I should clarify piston rock. It happens. However the one shown is the "good" hole so take it with a grain of salt. The real issue is heat. The upper land area is smaller than the skirt for that reason and in some engines way smaller to combat the rock issue along with heat. Fatten her up a hair next time out?
As stated this is an engine with an experimentational wrist pin (steel outer shell with an alum inner)